DNA的一级结构实质上就是()。A.DNA分子中的碱基排列顺序 B.DNA分子中的碱

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问题:

DNA的一级结构实质上就是()。

A.DNA分子中的碱基排列顺序

B.DNA分子中的碱基配对关系

C.DNA分子中各碱基所占的比例

D.DNA分子的双螺旋结构

E.DNA分子中的碱基种类

考点:生物学分子生物学分子生物学题库
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体会下列句中加粗词语的含义。   

(1)但是,另一位病人却纹丝不动地看着。 

答:_____________________________________

(2)他看到的只是光秃秃的一堵墙。   

答:_____________________________________    

题型:单项选择题

据国家标准《建筑施工场界噪声限值》,土石方工作夜间工作的噪声限值是( )。

A.60dB

B.55dB

C.50dB

D.45dB

题型:单项选择题

There has been much speculation about the origin of baseball. In 1907 a special commission decided that the modern game was invented by Abner Doubleday in 1839. One hundred years later the National Baseball Museum was opened to honor Doubleday. Historians, however, disagree about the origin of baseball. Some say that baseball comes from bat-and-ball games of ancient times. It is a matter of record that in the 1700s English boys played a game they called "baseball". Americans have played a kind of baseball since about 1800. At first the American game had different rules and different names in various parts of the country — "town ball", "rounders", or "one old cat". Youngsters today still play some of these simplified forms of the game.Baseball did not receive a standard set of rules until 1845, when Alexander Cartwright organized the Knickerbocker Baseball Club of New York City. The rules Cartwright set up for his nine-player team were widely adopted by other clubs and formed the basis of modern baseball. The game was played on a "diamond" infield with the bases 90 feet apart. The first team to score 21 runs was declared the winner. By 1858 the National Association of Baseball Players was formed with 25 amateur teams. The Cincinnati Red Stockings began to pay players in 1869.

Which of the following was NOT a predecessor of baseball

A.Rounders.

B.Town ball.

C.Cricket.

D.One old cat.

题型:单项选择题

泌尿系统最常用的辅助检查为

A.IVP

B.CT

C.KUB

D.B超

题型:单项选择题

二氧化碳提纯装置中,从精馏塔顶流入下道干燥工序的物料量为12吨/小时,塔顶回流量为2吨/小时,则该精馏塔的操作回流比为()

A、0.167

B、0.143

C、0.857

D、6

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